Increasingly, cameras are being used with computer and other electronic devices to record digital and analog images. For example, small mountable cameras, typically referred to as web-cams, are used with computers to capture still and video images that may be sent across a computer network. More recently, miniature cameras have been incorporated into cellular telephones and personal data assistants (PDAs) to store images that may be transmitted through wired and wireless techniques. In all these examples, the cameras offer the advantage of compactness and portability.
Unfortunately, the small size of these cameras translates into relatively low resolution and limited focus range. As a result of these limitations, such miniature cameras are used primarily in the image capture of objects that are relatively close to the camera. The web-cam, for example, is used mainly to capture images of a user at the computer and not to capture images of objects a substantial distance away from the camera.
While these cameras offer relatively good picture quality on these close-up images, they are nonetheless susceptible to imaging errors. One of the biggest imaging problems is attributable to the closeness of the objects being imaged. Objects that are close to the camera are typically close to the device with which the camera is being used. Cameras imbedded in a PDA, for example, capture images of objects in close proximity to the PDA screen. Cameras used as web-cams often capture images of objects that are close to both the camera and the computer monitor. Such objects are considered near-field objects.
If the PDA screen or the computer monitor is displaying an image of a sufficient brightness, in comparison to the ambient light, then a near-field object may have a distorted appearance depending on the color of that image being displayed. A computer operator sitting in front of a monitor displaying a bright red picture may appear to have an unnatural, pinkish tint to their skin tone. This is a result of the user being in the near field of the monitor and reflecting the red light produced by that monitor. The problem is particularly noticeable with white portions of an image. The “whites” will appear “off-white” to a camera. The problem is termed a color cast problem and is exacerbated when the computer, PDA, or other device is being used in a dark environment without ambient light. Here the light from the device is the only light illuminating the object, whose image is to be captured by the camera.